Modelling of supply and demand-side determinants of liquefied petroleum gas consumption in peri-urban Cameroon, Ghana and Kenya Matthew Shupler orcid.org/0000-0003-0259-91011, Judith Mangeni2, Theresa Tawiah3, Edna Sang2, Miranda Baame4, Rachel Anderson de Cuevas1, Emily Nix orcid.org/0000-0003-3331-20461, Emmanuel Betang4, Jason Saah3, Mieks Twumasi3, Seeba Amenga-Etego3, Reginald Quansah5, Elisa Puzzolo orcid.org/0000-0001-9177-52981,6, Bertrand Mbatchou4, Kwaku Poku Asante3, Diana Menya2 & Daniel Pope1 Nature Energy (2021)Cite this article Developing worldEnergy accessEnergy and behaviourEnergy supply and demand Household transitions to cleaner cooking fuels (for example, liquefied petroleum gas (LPG)) have historically been studied from a demand perspective, with clean energy usage expected to increase with improvements in household socio-economic status. Although recent studies demonstrate the importance of supply-side determinants in increasing clean cooking, few large-scale studies have assessed their importance quantitatively, relative to demand-related factors. Here, as part of the CLEAN-Air(Africa) study, we examine a population-based survey (n = 5,638) of cooking practices in peri-urban communities within Cameroon, Kenya and Ghana. Multilevel logistic and log-linear regression assessed the demand and supply-side determinants of LPG usage (primary versus secondary fuel) and consumption (kilograms per capita per year), respectively. Supply-side factors (for example, cylinder refill and transportation costs) and the use of single versus multiburner stoves were better predictors than household socio-economic status for both the probability of primarily cooking with LPG and the annual LPG consumption. These results highlight the need for policies that promote LPG supply and stove equipment to meet household needs. Polluting fuels, which include biomass (for example, wood and charcoal), coal and kerosene, are used by approximately 3.8 billion individuals worldwide for cooking, heating and lighting1. Household air pollution generated from incomplete combustion of these fuels results in levels of 2.5 μm fine particulate matter (PM2.5) typically well above World Health Organization (WHO) guidelines2. Exposure to PM2.5 in household air pollution is causally associated with many adverse health outcomes, which include cardiopulmonary and respiratory diseases3,4,5,6. Although fuels such as coal and charcoal generally emit lower levels of PM2.5 than other polluting fuels7, their combustion also generates high levels of carbon monoxide, which has been linked to increased blood pressure8 and adverse pregnancy outcomes9. Additionally, household air pollution contains short-term climate-forcing pollutants, which include black carbon, which is also associated with negative health impacts10. It is estimated that 25% of global anthropogenic black-carbon emissions are produced from household biomass combustion11,12. The use of polluting cooking fuel further leads to deforestation in certain locations, particularly in East Africa11. Women, typically the primary cook, may travel long distances to gather polluting fuels in some settings, which negatively impacts their livelihoods13,14.In Sub-Saharan Africa (SSA), approximately 900 million people cook with polluting fuels15. Governments in SSA, which include Cameroon, Ghana and Kenya, plan to expand the population-level use of liquefied petroleum gas (LPG) as a clean cooking solution to an aspirational target of 35–58% over the next decade16,17,18. LPG, although a fossil fuel, does not emit black carbon and has much lower PM2.5 emissions than polluting fuels7,16,19. Using LPG for cooking can also decrease localized deforestation and reduce the time spent gathering and cooking with polluting fuels7,20.Historically, studies focused on the determinants of clean cooking fuel use have emphasized the ‘household energy ladder’ model, by which improvements in socio-economic status (SES) lead households to transition to modern energy sources21,22,23. In reality, higher income usually does not lead to a complete transition to clean cooking fuels in low- and middle-income countries, as households will probably continue using polluting fuels alongside clean fuels (fuel ‘stacking’) to meet all cooking needs24. For example, studies in India found that resource-poor rural households provided with LPG cooking equipment under the Pradhan Mantri Ujjwala Yojana (PMUY) programme continued to use polluting fuels, which led to less frequent LPG use compared with that of more affluent urban households25,26. There are numerous potential causes of fuel stacking, which include taste preferences, high or unstable fuel costs, convenience and cultural norms27,28,29. In SSA, studies carried out in Cameroon30,31, Tanzania32 and Ethiopia33 also found supply-related issues to be important determinants of fuel stacking. Multinational modelling studies conducted in SSA found that community-level effects explained a higher amount of variability in cooking fuel choice than household SES characteristics, which suggests that cooking decisions may be largely driven by fuel availability and other supply-related factors that occur at a broader level34,35. Although these studies assessed the impact of specific supply and demand-side factors on primary cooking fuel type used, few large-scale studies quantitatively assessed determinants of a higher LPG consumption in SSA. To understand the important drivers of increased LPG consumption, rather than a binary indictor of whether LPG is used, may help uncover strategies that reduce fuel stacking and facilitate a full transition to LPG.In this study, survey data on cooking behaviours, which include the primary and secondary cooking fuels used and the average annual per capita LPG consumption, were collected in three peri-urban communities in Cameroon, Kenya and Ghana. These countries were specifically chosen as all are implementing policies to scale-up the adoption of LPG for cooking to decrease the negative impacts of polluting cooking fuels on health and the environment (Methods). Multilevel modelling of over 5,500 households from the three countries was conducted in a quantitative assessment of the supply and demand-related impacts on LPG fuel usage in the rapidly urbanising communities of SSA. The modelling results show a significant, positive relationship between increased per capita LPG consumption and lower LPG refill cost, shorter travel time to access the fuel and a higher number of LPG stove burners. Households that indicated a consistent availability of LPG refills at retailers had a significantly higher probability of using LPG as a primary cooking fuel (defined as the fuel used most often (Methods)) than those that reported an inconsistent supply, irrespective of education level and income. This empirical evidence suggests that to enhance LPG accessibility and availability, which includes via expansion of the number of retail points and promotion of multiburner LPG stoves, can be effective short-term interventions to increase the LPG consumption among peri-urban households in SSA.This study presents findings from the Global Health Research Group on clean energy access for the prevention of non-communicable disease in Africa through clean air (CLEAN-Air(Africa)) programme36, which involves a randomly administered cross-sectional survey via door-to-door sampling. Surveys were completed by the main cook of the household and included questions on cooking fuel use from a WHO harmonized survey for monitoring Sustainable Development Goal 7 indicators37. The full questionnaire is available in the Supplementary Information. The final analytical sample included 5,638 households (Obuasi, Ghana, 1,987 (35%); Mbalmayo, Cameroon, 1,811 (32%) and Eldoret, Kenya, 1,840 (33%)).The proportion of individuals who primarily cooked with LPG varied substantially by community (Obuasi 38% (n = 757), Mbalmayo 28% (n = 468) and Eldoret 5% (n = 35)) (Fig. 1). Of the households, 60% (n = 2,772) ‘stacked’ at least two cooking fuels. Fuel stacking was 30% higher among households that primarily used LPG (82%) compared with households that primarily used polluting fuels (53%). Fuel-stacking prevalence among households that primarily cooked with polluting fuels was approximately 20% higher in Eldoret (~60%) and Mbalmayo (~60%) compared with Obuasi (~40%) (Supplementary Table 2).Fig. 1: Primary cooking fuel types among three peri-urban communities in Ghana, Cameroon and Kenya.Cooking fuel percentages (n = 4,555) are presented among 757 households in Eldoret, rather than the full sample of 1,840 households because random sampling was switched to purposive sampling midway through the data collection. This was done to ensure a higher sample of LPG households available for subsequent phases of the CLEAN-Air(Africa) study in Eldoret.A higher percentage of households that primarily cooked with LPG contained a member with a university degree (22%) and were in the highest income quartile (23%), compared with households that primarily used polluting cooking fuels (5% with a university degree and 8% in the highest income quartile) (Supplementary Table 2). In Eldoret and Mbalmayo, the proportion of households cooking primarily with polluting fuels and reported seasonal changes in income (72 and 75%, respectively) was 20–30% higher than those that primarily cooked with LPG (42 and 58%, respectively). Among households that primarily cooked with LPG, 59% had fewer than five family members, compared with 38% of those that primarily cooked with polluting fuels (Supplementary Table 2).Over half (55%, n = 1,567) of the 2,830 households cooking with LPG used it as a primary fuel; very few (4%, n = 109) exclusively cooked with LPG and 44% (n = 1,263) used LPG as a secondary fuel (Table 1). In Obuasi, two-thirds of households reported using LPG as a primary fuel (67%, n = 679) compared with one-third (37%, n = 316) of households in Eldoret; in Mbalmayo, LPG was used roughly equally as a primary and secondary fuel (48%, n = 463). LPG was most frequently stacked with wood in Mbalmayo, and with charcoal in Eldoret and Obuasi (Fig. 2).Table 1 LPG usage characteristics among households that reported exclusive, primary or secondary use of LPG (n = 2,830)Fig. 2: Most common primary, secondary and tertiary cooking fuel combinations by community.For brevity, only the most common fuel combinations (>35 households) were included. Among the study households, there were nearly 200 different cooking fuel combinations.Nearly half (47%) of households that primarily cooked with LPG said it was not always available for purchase (Table 1), more than double that for those exclusively cooking with LPG (21%)). LPG consumption varied substantially from 0.8 to 67.0 kg capita–1 yr–1. Median LPG consumption was 14.4 kg capita–1 yr–1 (interquartile range (IQR) 10.4, 24.0) in Eldoret, 20.0 kg capita–1 yr–1 (IQR 15.0, 30.0) in Mbalmayo and 23.2 kg capita–1 yr–1 (IQR 14.5, 36.0) in Obuasi. The mean cost of cylinder refills was lowest among households exclusively cooking with LPG (US$0.99 kg–1 (s.d. 0.50)) and highest among households using LPG as a secondary fuel (US$1.27 kg–1 (s.d. 0.67)).In Eldoret, 72% of the participants cooking exclusively with LPG were ten minutes or less from a retailer compared with 47 and 36% of households using LPG as a primary or secondary fuel, respectively. Electing to walk to an LPG retailer to obtain cylinder refills was six times more common among participants in Eldoret using LPG exclusively (61%) than among those using LPG as a secondary fuel (11%).The final multivariable model modestly characterized (pseudo (R_{{rm{marginal}}}^2) = 0.42, receiver operating characteristic = 0.82) primary versus secondary use of LPG for cooking (Supplementary Table 4). Demographics ((R_{{rm{marginal}}}^2) = 0.11) and LPG supply-related factors ((R_{{rm{marginal}}}^2) = 0.10) explained a higher proportion of model variability than SES ((R_{{rm{marginal}}}^2) = 0.03) (Supplementary Table 4). Households with 1–2 members had more than twice the predicted probability (84% (95% CI, 68, 93)) of primarily using LPG than households with 7–8 family members (35% (95% CI, 17, 58)) (Table 2). Lower availability of LPG and higher refill costs were associated with a lower predicted probability of primary use of the fuel in a monotonically decreasing manner (Fig. 3). Specifically, 69% (95% CI, 47, 85) of households that report a refill cost of US$1.10 kg–1, respectively. As the number of family members living in the household increased, a higher number of LPG stove burners was associated with a greater proportion of households that reported the use of LPG as a primary fuel; nearly 60% of households with a large family size (≥7 members) using LPG as a primary cooking fuel owned a 3–4 burner stove, compared with less than 30% of smaller households (1–2 members) that primarily cooked with LPG (Supplementary Fig. 1).Table 2 Coefficients from LPG primary versus secondary cooking fuel logistic regression modelFig. 3: Average-adjusted predicted probabilities of using LPG as a primary versus secondary cooking fuel.Mean predicted probability of using LPG as a primary fuel along with error bars that represent 95% confidence intervals (CIs). Primary LPG households were those that indicated LPG as their main cooking fuel, whereas secondary LPG users were those that stated LPG was another fuel they used aside from their main cooking fuel. All probabilities account for quantitative covariates centred at their mean.Half ((R_{{rm{marginal}}}^2) = 0.49; cross-validation R2 = 0.39) of the variability in LPG consumption was explained by covariates included in the final model (root mean square error = 0.52 kg capita–1 yr–1; cross-validation root mean square error = 0.54 kg capita–1 yr–1) (Supplementary Table 5). Household demographics ((R_{{rm{marginal}}}^2) = 0.31) explained substantially more of this variability than household SES ((R_{{rm{marginal}}}^2) = 0.0). Households with 3–4 members consumed an average of 13.7 kg capita–1 yr–1 (95% CI, –17.2, –9.4), less than households with 1–2 individuals (Table 3).Table 3 Coefficients from log-linear regression and exponentiated consumption (kg capita–1 yr–1 from LPG consumption modelHouseholds that used a double-burner or triple-burner LPG stove consumed an average of 8.1 (95% CI, 3.6, 13.8) or 6.7 (95% CI, 2.4, 11.7) kg capita–1 yr–1, respectively, more LPG than households with single-burner stoves, irrespective of SES and family size (Table 3). Households that exclusively cooked with LPG consumed 2.5 kg capita–1 yr–1 (95% CI, 0.4, 4.3) more than households that stacked LPG with another fuel (Table 3).Participants that required 11–20 minutes, 21–30 minutes or >30 minutes to travel to LPG retailers consumed an average of 0.9 (95% CI, –3.9, 2.9), 1.2 (95% CI, –4.2, 2.7) and 1.3 (95% CI, –4.2, 2.4) kg capita–1 yr–1 les
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Modelling of supply and demand-side determinants of liquefied petroleum gas consumption in peri-urban Cameroon, Ghana and Kenya
